The objective of this project is to improve diagnostic techniques for breast cancer and breast ductal carcinoma in situ (DCIS). The hypothesis being tested is that vasopressin (VP)-related peptides, and VP receptors will provide sensitive and reliable targets for better detection, diagnosis, and eventual treatment of breast cancer and DCIS. Our recent data show VP gene expression is a feature common to all or most breast cancers and DCIS. This expression gives rise not only to a surface marker, GRSA, but also to VP, VP-related glycopeptide (VAG) and ProVP as potential blood markers of disease. Vasopressin receptors also seem to be expressed because VP is an autocrine growth factor for breast cancer. Goals are directed towards: (i) developing effective plasma and tissue ELISA assays for detecting ductal and lobular invasive breast cancer; (ii) assessing the value of such ELISA assays for detecting residual invasive disease and possibly forecasting survival; (iii) ascertaining if the same ELISA assays can be utilized for detecting DCIS in plasma as they most probably can in tissues; and (iv) determining the distribution and abundance in breast cancer and DCIS of an abnormal VP receptor (abnV2R) that is seemingly unique to breast cancer to ascertain if it can be used as a new marker for detection and treatment of breast cancer. These investigations will employ, RIA as well as ELISA assay, RT-PCR, cloning, and DNA sequencing, immunohistochemistry, antibody generation, Western analysis with densitometric quantitation, and flow cytometry. One successful end-point of our studies would be the generation of widely available and sensitive methods for detecting and localizing disease in all, or most, individuals. Another successful end-point would be the finding that these same methods can successfully monitor current treatments, and potentially lead to new and more effective ones.